Actively exploited · Published Jun 23, 2026 · Assigned by GitHub_M
CVE-2026-55255Langflow: IDOR Vulnerability in `/api/v1/responses` Endpoint Allows Authenticated Attackers to Access Another User's Flow
High 8.4 Exploited
In plain English
A high-severity authorization bypass via user-controlled key in langflow from langflow-ai. Attackers are actively exploiting it in the wild (listed by CISA on July 7, 2026). The chance it is exploited in the next 30 days is estimated at 0.9% (higher than 59% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.
CISA guidance
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Federal agencies must remediate by Jul 10, 2026.
Official description
Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.1, an Insecure Direct Object Reference (IDOR) vulnerability in /api/v1/responses endpoint allows an authenticated attacker to execute any flow belonging to another user by specifying the victim's flow ID in the request. This vulnerability is fixed in 1.9.1.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | langflow | 1.9.1 | GHSA-qrpv-q767-xqq2 |
| PyPI | langflow | 1.9.2 | PYSEC-2026-221 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| langflow-ai | langflow | < 1.9.1 |
Weakness: CWE-639 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L
References
- https://github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2 x_refsource_CONFIRM
- https://github.com/langflow-ai/langflow/pull/12832 x_refsource_MISC
- https://github.com/langflow-ai/langflow/commit/2c9f498d664a3c32698b57d7c5e752625291060e x_refsource_MISC
- https://webflow.sysdig.com/blog/understanding-langflow-cve-2026-55255-and-why-higher-cvss-vulnerabilities-arent-always-the-most-exploited third-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-55255 government-resource